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My truck is a 99 K3500 6.5td Crew Cab. Several months ago I finally got everything together to swap my auto transmission for the manual NV 4500. It was the best thing I have done to my truck. I used to curse it on every trip because the automatic did not give me any control over shifts and I new it was wasting fuel. With the cruise on it would often shift down and rev the engine just before cresting a hill. On really hard pulls up steep grades out west the TCC would unlock and generate tons of heat so that the engine would over heat. I have always had a manual to pull things with but I thought I would give the auto a try. I don't plan on doing that again.
Anyway several people have asked me for details on my trans swap so I thought I would post it so that others could get the info.
I got my NV4500 from a 4x4 accessories company out of Alabama that I found on the internet. They were easy to deal with and I got a brand new NV4500 for $1910 delivered. This was not much more than I could get a rebuilt for.
My bell housing, single mass flywheel, through out brg, concentric slave cylinder and master clutch cylinder came from another diesel page member that only had a 6k miles on these parts. I gave $450 delivered for this. My other option I was considering on these parts was to buy a new clutch from Kennedy or Heath which when I checked one of them had the clutch and flywheel parts for $384. The rest of these parts I was trying to find from a salvage yard but manual parts are hard to find.
I had to buy the clutch pedal and bracket from a local dealer that gives a substantial discount on parts. These cost me about $100. The pedal, master, slave and bracket has to come from a 97 or newer. The older ones are a different style.
I got the shifter stick and boots from a salvage yard for about $20. They were from an early 90
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Thats sounds like a winner.Your truck sounds very custom with some of the things you did.I would like to see pictures if you ever get a chance.I had a ext cab dually that I wanted to switch to single rear wheels but traded it in for what I have now.I would like to see how your conversion came out.I know yours is a crew,but I always wondered why gm didnt come out with a srw ext cab 1 ton,thats what I wanted.
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Hi there,
Very well done, sounds like you did your homework
followed up by a good job.
Any chance you could let us have the name of the supplier for the gearbox unit.
I have priced reconditioned NV4500's in the past and as you say the new unit was well worth it.
Also a proper article for the DP would not be too far away.
Best regards and Happy stirring,
Jim Twaddle
Biggar, Scotland jim@jimmyt.plus.com
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I bought the NV4500 from tellico4x4.com. They are in Alabama. Also they were very helpful making sure I got the right transmission.
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Another expense I forgot to mention was the $60 worth of GM synthetic gear lube it requires to keep your warrnty on the new trans.
Also another modification that had to be done was the tranfer case shifter linkage needed to be shortened. This I did by cutting a section out of it and welding it back together.
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Only one thing I might have done diferent.
Put a switch in the circut that activates the front differential lock. When its time to back up a trailer its so much easier to put the transfercase in low range, saves wear and tear on the clutch. The switch unlocks the front diff for no front end chatter.
The only time I wish I had a slushbox is when I need to back a trailer up realy slow, to get in to a tight spot.
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Good job JD.
If you are keeping track what was your MPG increase both towing and bobtail?? I ask because nobody believes me when I tell them it is 5 mpg (bobtail) difference between the NV4500 and the auto, since you have the same truck it the extra MPG has to be comming from the NV4500.
Thanks
Al
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I still need to get with you and bring my truck down there and compare clutches mine is really stiff. I took back down to the shop that put the engine i nand they said it is put in correctly so I going to go back down to the shop that put the master and slave cylinder in and have them look into that. But I still have to get my G$%^&&#M foot out of a cast.
Rick :(
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I am estimating that the NV4500 gives me about 1-2 mpg better. That would be highly dependent on the way you drive. Mine is 80% interstate pulling 4k lbs. This condition is close to where the auto would do its best. Any time the auto is locked with the TCC I would not expect the mpg to be much different. However if the torque converter is slipping it is wasting significant HP and fuel.
When I pulled hard in the mountains with the auto in 2nd at a given rpm the speed would be about 25mph. On the level in 2nd with the same rpm the speed would be about 45mph. This is a tremendous waste of power because the slip is wasting hp. Under these conditions the manual should be much greater than the auto. And not nearly the heat load on the radiator.
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Where you will notice the difference in the 6 spd, is when you have to pull in 3rd vs 4th for the 6 spds, the gear below Direct is a 1.3X in the 6 spd vs a 1.6x with the 5 spd. That difference alone will net you about +5 mph more speed at a given RPM with the 6spd over the 5 spd. I go about 35 at 2600 RPM's in 3rd, where a 4th in a 6spd would net me about 40-45 or so at 2600 R's. I personally wish I had a ZF or NV 6 spd over my NV4500 for that reason alone. Also the ZF has a lower first gear than the NV, 5.79 vs 5.64, so a bit more grunt to get things going all other things being equal. Otherwise, I enjoy the manual's over the auto's also.
I'll SWAG that Al probably gets the 5 mpg more than most of the auto versions because of the 3.42 axle gears vs most of us having 4.10's in the pumpkins. But could be wrong there too! :rolleyes:
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Whether the ZF6 is worth it is highly dependent on the load you pull. With my 4Kcamper there is seldom a hill that I can't go up in 4th so the extras gears would have marginal value.
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JD. Thanks a million for your post. It's just what I've been waiting for.
I haven't had problem one with my L80E in 174K miles. But, I grew up on shifting for myself, and after driving the Sub. for many thousands of miles and over six years, I still find myself lifting my left foot to hit the clutch about twice a year! Senility is setting in early, I guess.
Anyway, if and when I have a problem with the slush box, you can bet I'll be looking up your post on the CD and tooling up for a transmission swap.
Great way to go, JD! Thanks again.
Dick Wells
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:eek: changing auto to manual trans? i have nv4500, but i like more automatic transmission [img]smile.gif[/img] but okay, i dont tow anything :rolleyes:
